A container typically has a circular cross-section. However, the diameter of the section is not constant as a function of height along the container. Many containers have a container wall that, at some height, has a diameter that is greater than the container's diameter at other heights. This section is often called a “ring” or “rolling ring.”
When containers of this type are glued to form a cluster pack, there is a risk that the containers will tear when being separated. In particular if they are connected by glued joints in the lower half of the containers, the resulting leverage that arises during container separation is substantial.